Aquatic Zeal

First off Gishki; they are a water archtype that focuses on rituals. The ones currently out are interesting but not all that great.

The money's at Evigishki Zeal Gigas
Water/Aqua/Effect/Ritual/10/3200/0
Cannot be Normal Summoned or Set. Must first be Ritual Summoned. You can Ritual Summon this card with any "Gishki" Ritual Spell Card. Once per turn: You can pay 1000 Life Points; draw 1 card, and reveal it. If it is a "Gishki" monster, shuffle 1 card on the field to the Deck.

It's a rather nice beatstick with a nice effect. For a mere 1000 lp you get a draw. If that draw happens to be a Gishki monster your opp loses a card to the deck.
Now Zeal Gigas isn't due out until HA07 so we have some time til then to gather the deck pieces.

The key ritual spell is Gishki Aquamirror.
Ritual Spell
This card can be used to Ritual Summon any "Gishki" Ritual Monster. You must also Tribute monsters from the field or your hand whose total Levels equal the Level of the Ritual Monster you Ritual Summon. You can shuffle this card from the Graveyard into the Deck to target 1 "Gishki" Ritual Monster in your Graveyard; return that target to your hand.

There are 2 other ritual spells but they aren't nearly as good as Aquamirror.
Forbidden Arts combines a ritual spell with Soul Exchange while cutting the summoned monster's atk in half. Not worth it.
Duplicate Soul Mirror costs a minimum of 2000 lp to summon a ritual. Also not worth it.

Now that we've covered the rituals, let's cover the engine.

Gishki Shadow
Water/Sea Serpent/4/Effect/1200/1000
If you Ritual Summon a WATER Ritual Monster, this 1 card can be used as the entire Tribute. You can discard this card; add 1 "Gishki" Ritual Spell Card from your Deck to your hand.

Grab Aquamirror and if need be tribute it for a ritual.

Vision Gishki
Water/Sea Serpent/2/Effect/700/500
If you Ritual Summon a WATER Ritual Monster, this 1 card can be used as the entire Tribute. You can discard this card; add 1 "Gishki" Ritual Monster from your Deck to your hand.

Same as Shadow but for a monster.

Gishki Abyss
Water/Fish/2/Effect/800/500
When this card is Summoned: You can add 1 "Gishki" monster with 1000 or less DEF from your Deck to your hand, except "Gishki Abyss".

The deck's Manju. It'll either grab a Shadow or Vision which will then grab its respective target.

Gishki Ariel
Water/Spellcaster/4/Effect/1000/1800
FLIP: You can add 1 "Gishki" monster from your Deck to your hand.

The deck's recruiter, very similar to Worm Cartaros. Rather nice def so it'll have a chance to sit on the field.

Gishki Beast
Water/Beast/4/Effect/1500/1300
When this card is Normal Summoned: You can target 1 Level 4 or lower "Gishki" monster in your Graveyard; Special Summon that target in face-up Defense Position.

Beast opens the door for exceeds or grabbing a Shadow/Vision for a desperate ritual summon.

Gishki Chain
Water/Sea Serpent/4/Effect/1800/1000
When this card is Normal Summoned: Look at the top 3 cards of your Deck and if there is a Ritual Monster or Ritual Spell Card among those cards; you can reveal it to add it to your hand and return the remaining cards to the top of the Deck in any order.

Allows for stacking and can grab a missing ritual piece. Cuts luck out of Gigas's effect.

So the skeleton should look like this:
3 Evigishki Zeal Gigas
3 Gishki Shadow
3 Vision Gishki
2 Gishki Abyss
3 Gishki Ariel
3 Gishki Beast
2 Gishki Chain

3 Gishki Aquamirror

Non theme support covers a fair amount of cards, most notably Salvage and Surface.
Salvage grabs Vision and Shadow for more deck thinning or that necessary ritual tribute. It'll also grab Beast and Ariel if you need walls (Beast into Utopia).
Surface works well with Abyss and Vision. Summon Abyss>grab Vision>dump for ritual>Surface to revive Vision>overlay for Gachi.

Next is staple spells/traps.

Here's my current build I've enjoyed on DN:
21
3 Evigishki Zeal Gigas
3 Gishki Ariel
3 Gishki Beast
2 Gishki Chain
3 Gishki Shadow
3 Vision Gishki
2 Gishki Abyss
2 Tragoedia

16
3 Salvage
2 Surface
Monster Reborn
Heavy Storm
Dark Hole
Book of Moon
Mind Control
3 Mystical Space Typhoon
3 Gishki Aquamirror

3
3 Royal Decree

The extra is up to you but I'd include:
2 Number 39: Utopia
Gustaph Max, Super Dreadnought Cannon Express

Gustaph Max is a lvl10 exceed that deals 2000 damage by detaching a material. It also has 3000 atk and def. Summon and atk with 2 Gigas then overlay into Max for 2000 more damage. If done right it'll be game.

Trag provides a bit of def should you get hit plus it's lvl10 for Gigas.
Triple MST allows the deck a chance to be more aggro.
Mind Control steal lvl4s for Utopia.
With the heavy monster and spell count, Decree helps shut down the traps that'll get in the way, most notably Warning.

Quick note for summoning the rituals: Using actual monsters to add up to 10 or whichever lvl you need is not all that efficient. The optimal play is to grab an Aquamirror and 2 copies of the ritual monster. Tribute one copy to summon the second and then use Aquamirror's effect to add that first copy to your hand and shuffle Aquamirror back into the deck.

Hoped you enjoyed the article. This is the Island of Lost Cards, saving all the Gishki supers from Hidden Arsenal. We'll be right back after these commercials.